One basic problem with a standard refrigerator compressor is the inefficiency of the compressor due to the friction generated by the piston drive mechanism in the standard compressor. A standard reciprocating refrigerator compressor uses a motor to rotate a crankshaft, which in turn moves a piston up and down within a compression chamber. Referring to FIG. 1, a typical refrigerator compressor 10 is shown. More specifically, the induction motor 12 creates a torque on the crankshaft 14 which causes the piston 16 to move back and forth within the cylinder 18 via a connecting rod 20. During operation, the force exerted by the compressing gas is transferred through the piston's spherical bearing 22 down the connecting rod 20 to the connecting rod bearing 24 and and finally to the crankshaft bearings 26. These bearings are all heavily side loaded, creating a great amount of friction. As a result, the bearings must be continuously lubricated to prevent the heat build-up which will eventually burn out the bearing.
Therefore, a need exists for a compressor driver that provides the required piston movement without producing undesired amounts of friction.
Another problem with the standard compressor is that its manufacturing process is complex, and therefore relatively expensive. The conventional induction motor in the compressor is constructed from a laminated stack of silicon-iron sheets, with a copper coil complexly woven throughout. The motor's stator is assembled by stamping appropriately-shaped individual laminates from a coiled sheet silica-iron. Typically over one hundred individual laminates are required. The laminates are varnished, stacked in a jig, and welded along the side to create one integral unit. Coil slots and holes are machined into the stacked assembly, and plastic insulation inserts are placed in the slots and holes. Copper wire is then woven into the inserts by a complex coil winding machine. The coil extensions are then machine stitched, the entire assembly vacuum impregnated with epoxy, and baked. Similarly, the conventional compressor's rotor assembly requires stacked laminates, wherein the number of laminates and the process of stacking is identical to that required for the stator.
The standard compressor further requires three precision bushings and and a complex spherical bearing. These parts require precision grinding and hardened materials to provide the requisite durability. Therefore, the manufacturing process of the conventional compressor requires extensive equipment and processing, and is therefore a costly process. In comparison, in the compressor of the present invention, the manufacturing process is simple, does not require the above-discussed complex manufacturing process, and only requires precision grinding for the piston and cylinder. Furthermore, the compressor of the present invention uses considerably less copper wire than the typical compressor, and therefore is less expensive in material costs.
Therefore, a need also exists for a compressor that is inexpensive and relatively simple to manufacture.